NUCLEATION OF SUPERCONDUCTIVITY IN A THIN DISK WITH A RING-LIKE DEFECT

2013 ◽  
Vol 27 (04) ◽  
pp. 1350025 ◽  
Author(s):  
J. BARBA-ORTEGA ◽  
EDSON SARDELLA ◽  
J. ALBINO AGUIAR
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
External Magnetic Field ◽  
Vortex State ◽  
Thin Disk ◽  
Pinning Force ◽  
Magnetization Curves ◽  
Disk Plane ◽  
Circular Defect ◽  
Superconducting Sample

We report on the influence of a circular defect on the vortex configuration in a mesoscopic superconducting sample. Effects associated with the pinning force of the circular defect on the configuration and on the vortex entry fields are studied for a very thin disk. We calculate the magnetization loop, vorticity, free energy and superconducting electrons for the disk in presence of an external magnetic field applied perpendicular to the disk plane. The magnetization curves are hysteretic, with paramagnetic response in part of the downward branch, also, in this part we found a vortex–anti-vortex state.

EFFECTS OF INTERNAL DEFECT ON THE VORTEX ENTRANCE IN MESOSCOPIC SUPERCONDUCTOR

2013 ◽  
Vol 27 (11) ◽  
pp. 1350075 ◽  
Author(s):  
J. BARBA-ORTEGA ◽  
MIRYAM R. JOYA ◽  
GILMAR E. MARQUES
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
Thin Disk ◽  
Cooper Pairs ◽  
Pinning Force ◽  
Internal Defect ◽  
Mesoscopic Superconductor ◽  
Defect Position ◽  
Disk Plane ◽  
Superconducting Sample

In this paper, we report on the influence of an internal defect on the vortex entrance in a mesoscopic superconducting sample. Effects associated to the pinning force of the defect on the configuration and on the vortex entry fields are studied for a very thin disk. We calculate the supercurrent, magnetization, vorticity, free energy and Cooper pairs density for a disk in presence of external magnetic field applied perpendicular to the disk plane. Due to vortex–defect attraction (repulsion), the vortices always (never) are found to be sitting on the defect position.

Thermodynamics of Bidisperse Ferrofluids in Zero External Magnetic Field: Theory and Simulations

2015 ◽  
Vol 233-234 ◽  
pp. 331-334
Author(s):  
Anna Yu. Solovyova ◽  
Ekaterina A. Elfimova
Keyword(s):  
Magnetic Field ◽  
Field Theory ◽  
Free Energy ◽  
External Magnetic Field ◽  
Volume Concentration ◽  
Helmholtz Free Energy ◽  
Hard Spheres ◽  
Particle Volume ◽  
Simulation Data ◽  
Theoretical Predictions

The thermodynamic properties of a ferrofluid modeled by a bidisperse system of dipolar hard spheres in the absence of external magnetic field are investigated using theory and simulations. The theory is based on the virial expansion of the Helmholtz free energy in terms of particle volume concentration. Comparison between the theoretical predictions and simulation data shows a great agreement of the results.

Biodegradation of Nanoparticles in a Body from Mössbauer and Magnetization Measurements

2012 ◽  
Vol 190 ◽  
pp. 725-728 ◽  
Author(s):  
Mikhail Chuev ◽  
Valery Cherepanov ◽  
Maxim P. Nikitin ◽  
Mikhail Polikarpov
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Magnetic Nanoparticles ◽  
External Magnetic Field ◽  
Chemical Transformation ◽  
Living Organism ◽  
Quantitative Information ◽  
Spectral Shape ◽  
Magnetization Curves ◽  
Field Dependent

In order to extract a quantitative information about characteristics of the magnetic nanoparticles injected into a living organism one has to define a model of the magnetic dynamics in order to fit self-consistently the whole set of the experimental data, particularly, the evolution of Mössbauer spectral shape with temperature and external magnetic field as well as the magnetization curves. We have developed such a model and performed such an analysis of the temperature-and magnetic field-dependent spectra and magnetization curves of nanoparticles injected into a mice. This allowed us to reliably evaluate changes in the residual nanoparticles characteristics and their chemical transformation to paramagnetic ferritin-like forms in different mouses organs as a function of time after injection of nanoparticles. Actually, the approach allows one to quantitatively characterize biodegradation and biotransformation of magnetic nanoparticles injected into a body.

scholarly journals Vortex guide under a Lorentz force

2020 ◽  
pp. 101-106
Author(s):  
C. A. Aguirre ◽  
Q. Martins ◽  
Jose Barba
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
External Magnetic Field ◽  
Lorentz Force ◽  
Vortex State ◽  
Cooper Pairs ◽  
Magnetic Response ◽  
External Current ◽  
Critical Temperatures ◽  
Ginzburg Landau

In the present work we studied the effect of the nature of the contacts, by which a weak external current is applied, in an anisotropic superconducting rectangle, on the magnetization, magnetic susceptibility, density of the Cooper pairs and  (magnetic field for which the first vortices entry on the sample). The contacts are simulates by the  parameter, and the anisotropy is present in sections with different critical temperatures modeling for  function, both in the Ginzburg-Landau formalis. Also, the sample is embebbed in an external magnetic field . We established how the nature of the contacts and the presence of a weak Lorentz Force, influence the magnetic response and the vortex state of the sample.

Equilibrium configurations of Vlasov plasmas carrying a current component along an external magnetic field

1972 ◽  
Vol 7 (3) ◽  
pp. 445-459 ◽  
Author(s):  
J. R. Kan
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
External Magnetic Field ◽  
Constant Field ◽  
Current Component ◽  
Equilibrium Solutions ◽  
Plasma Parameters ◽  
Equilibrium Configurations ◽  
Field Aligned Current ◽  
A Current

A class of equilibrium configurations of Vlasov plasmas carrying a current component along an external magnetic field is presented. The present slab model contains the diamagnetic current jy, and the field-aligned current jz for arbitrary βc (= particle pressure/magnetic pressure of the applied constant field). For fixed βc and field-aligned current, our model admits a family of equilibrium solutions in which the diamagnetic currents range from zero to a maximum value. The amount of diamagnetic current flowing in a machine depends on the width of the machine, the field-aligned current and other plasma parameters. The Helmholtz free energy of the system is calculated under the constraints that the total number of particles and the field-aligned current are conserved. The least unstable equilibrium configuration in a machine is obtained by minimizing the free energy under the stated constraints among all equilibria whose plasma widths do not exceed the width of the machine.

LARGE DEVIATIONS AND THE RANDOM ENERGY MODEL

2001 ◽  
Vol 15 (01) ◽  
pp. 1-15 ◽  
Author(s):  
T. C. DORLAS ◽  
J. R. WEDAGEDERA
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
External Magnetic Field ◽  
Large Deviation ◽  
Error Correcting Codes ◽  
Energy Model ◽  
Random Energy Model ◽  
Recent Letter ◽  
Random Energy ◽  
Deviation Property

We present a simple proof of the formula for the free energy of the random energy model using a large deviation property which holds almost surely with respect to the randomness. This proof is extended to the case with external magnetic field leading to the solution of a model with higher-order ferromagnetic term. It is shown that this model is useful for Sourlas' application to error-correcting codes as was already pointed out in a recent letter by the authors.

scholarly journals Excitation of electrostatic ion-cyclotron-like modes by the electron density ripple in dusty magnetoplasmas

2009 ◽  
Vol 75 (4) ◽  
pp. 433-436
Author(s):  
P. K. SHUKLA
Keyword(s):  
Magnetic Field ◽  
Free Energy ◽  
External Magnetic Field ◽  
Electron Density ◽  
Mathieu Equation ◽  
Ion Cyclotron ◽  
Unstable Solutions

AbstractIt is shown that electrostatic ion-cyclotron (EIC)-like modes can be excited by the pre-existing electron density ripple across the external magnetic field in a dusty magnetoplasma. For this purpose, we use the ion continuity and momentum equations, together with the Boltzmann-distributed electrons, and derive the standard Mathieu equation. The latter admits unstable solutions, demonstrating that the EIC-like modes in dusty magnetoplasmas can be driven due to the free energy in the electron density ripple.

Magnetic Anomaly in the YBa2Cu3O7 System at Low External Magnetic Fields

1992 ◽  
Vol 275 ◽  
Author(s):  
Bokhimi
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Anomaly ◽  
Normal State ◽  
Vortex Lattice ◽  
Sample Temperature ◽  
Zero Field ◽  
Magnetization Curves ◽  
Diamagnetic Signal

ABSTRACTMagnetization curves for low external magnetic fields of field-cooled superconducting YBa2Cu3O7 samples show an increase in the diamagnetic signal when the sample temperature is near the transition to the normal state. The Increase of the diamagnetic signal depends on the external magnetic field (H ≤ 13.5 Oe). The effect is observed when the samples are field-cooled, but not when they are zero-field-cooled, that means that it is related with the behavior of the vortex lattice.

Influence of short-range artificial defects in a macroscopic flat disk on the Abrikosov state

2014 ◽  
Vol 28 (32) ◽  
pp. 1450227 ◽  
Author(s):  
Jesús González Acosta ◽  
Miryam R. Joya ◽  
J. Barba-Ortega
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Short Range ◽  
Theoretical Study ◽  
Thin Disk ◽  
Cooper Pairs ◽  
Vortex Pattern ◽  
Pinning Effect ◽  
Flat Disk ◽  
Barrier Defect

We study the vortex configuration in a superconducting macroscopic flat disk with central defects in the presence of a uniform applied magnetic field. Owing to the defects nature on the thin disk, vortices are able to form geometry induced, quasi-symmetric configurations of disk, triangle and concentric shells in the rest of the disk. The theoretical study made on this mesoscopic systems allows us to trace not only how the vortex pattern evolves with magnetic field, but also how the defect can be used to show the pinning and anti-pinning effect. The magnetic induction, vortex number, magnetization and Cooper pairs density as a function of the external magnetic field are calculated, we show that in our sample novels vortex configurations are possible due to the size of the disk and if the hole or barrier defect is considered.

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